Saturated steam quality measurement system and method

ABSTRACT

The present invention provides for a system and method for determining saturated steam quality. The system includes a liquid inlet in communication with a pre-boiler stream of liquid creating a liquid inlet flow. An inlet chamber is in communication with the liquid inlet flow and has a inlet temperature compensated conductivity probe that is submerged in the liquid inlet flow and configured to measure the conductivity of the inlet liquid. A liquid outlet is in communication with a post-boiler outlet flow creating an outlet liquid flow. An outlet chamber is in communication with the outlet liquid flow. The outlet chamber has an outlet temperature compensated conductivity probe that is submerged in the outlet liquid flow and configured to measure the conductivity of the outlet liquid. A processor is in communication with the inlet and outlet temperature compensated conductivity probes and configured to calculate steam quality. The processor is further in communication with boiler control system wherein boiler control system is configured to adjust boiler firing rate and/or liquid flow rate based on the calculated steam quality. The method includes steps to measure the conductivity of the liquid inlet flow and outlet liquid flow and to calculate the saturated steam quality.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention is generally directed toward saturated steam quality, and more specifically, toward a system and method for measuring saturated steam quality.

Background

When water changes from liquid to vapor, any dissolved or suspended solids, such as sodium salts, calcium, magnesium, iron, copper and dust, within the water will fall out. In the case of a boiler that utilizes water that contains dissolved or suspended solids, this fall out can cause damage, such as scaling and fouling of the boiler tubes. Accordingly, boilers must control the saturated steam quality in order to allow for these dissolved or suspended solids to be removed from the boiler.

In the prior art, the measuring of the conductivity of the water is one technique to determine the level of saturated steam quality. When boiler water is carried over in steam, the dissolved or suspended solids content of the boiler water contaminates the steam, and steam sample conductivity increases. Manual measurement of this increase provides a reasonably accurate method for determining steam quality. However, this technique is not efficient. This technique cannot be performed directly in high pressure or high temperature, and requires specialized equipment. Since the liquid stream exiting the boiler is under high pressure at a high temperature, this technique is performed manually, usually only a few times per day.

Thus, there is a need for an improved system and method for measuring saturated steam quality.

BRIEF SUMMARY OF THE INVENTION

The present invention satisfies the needs discussed above. The present invention is generally directed toward saturated steam quality, and more specifically, toward a system and method for continuously measuring saturated steam quality.

One aspect of the present invention is directed toward a system for continuously measuring saturated steam quality. The system includes a liquid inlet in communication with a pre-boiler stream of liquid creating a liquid inlet flow. An inlet measurement chamber is in communication with the liquid inlet flow. This chamber has an inlet temperature compensated conductivity probe that is submerged in the liquid inlet flow and configured to continuously measure the conductivity of the inlet liquid.

The system also includes a separated liquid outlet in communication with a post-boiler outlet liquid flow. In this aspect, the separated liquid outlet is at least one liquid separator. An outlet measurement chamber is in communication with separated outlet liquid flow. This chamber has an outlet temperature compensated conductivity probe that is submerged in the separated outlet liquid flow and configured to continuously measure the conductivity of the outlet liquid.

Due to both the liquid inlet flow and separated liquid outlet flow being under high pressure at high temperature, both flows are subject to adjustment of their operational conditions which include a reduction of the temperature and pressure. In this aspect, this is performed by at least one cooler and at least one pressure valve for each flow.

A processor is in communication with the inlet and outlet temperature compensated conductivity probes. It is configured to calculate steam quality of the post-boiler outlet flow. Further, it is in communication with the boiler control system. The boiler control system is configured to adjust boiler firing rate and/or liquid flow rate to achieve the desired steam quality of the post-boiler outlet flow.

An additional aspect of the system of the present invention includes the processor being in communication with multiple boilers, along with a display device to display steam quality measurement.

Another aspect of the present invention is directed toward a method of measuring saturated steam quality. This aspect includes measuring pre-boiler conductivity of a liquid prior to entering a boiler, measuring post-boiler conductivity of the liquid exiting the boiler and calculating the level of saturated steam quality of the post-boiler outlet flow based on the pre-boiler conductivity and post-boiler conductivity measurements of the liquid. The measuring of conductivity is performed by utilizing a temperature compensated conductivity probe. The calculating of the level of saturated steam quality is performed by utilizing processor based control system. Further, this aspect includes transmitting the calculated level of saturated steam quality to the boiler control system. This will allow the boiler control system to achieve the desired steam quality by adjusting the boiler firing rates and/or the liquid flow rates.

Further, as samples of both the liquid inlet flow and the post-boiler outlet flow are under high pressure at high temperature, this aspect includes adjusting the operational conditions of both flows which includes reducing the temperature and pressure of both flows. In this aspect, the operation condition for the temperature is less than the saturation point and for the pressure is near ambient.

Another aspect of the method of the present invention includes the steps set out above with the addition of recovering the liquid from both flows after the conductivity measurement.

It is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein are for the purpose of description and not of limitation.

Upon reading the above description, various alternative embodiments will become obvious to those skilled in the art. These embodiments are to be considered within the scope and spirit of the subject invention, which is only to be limited by the claims which follow and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration an embodiment of system of the present invention.

FIG. 2 is a flowchart of an embodiment of method of the present invention.

DESCRIPTION OF THE INVENTION

The present invention satisfies the needs discussed above. The present invention is generally directed toward saturated steam quality, and more specifically, toward a system and method for continuously measuring saturated steam quality.

FIG. 1 is a schematic illustration an embodiment 10 of the system to measure saturated steam of the present invention. This embodiment 10 includes a boiler 12 having liquid inflowing 14 therein and a post-boiler outlet stream 16 flowing out therefrom. In this embodiment, the liquid is water. The use of water is merely illustrative. Those skilled in the art will recognize that other suitable liquids may be used within the present system.

A liquid inlet 18 is in communication with the inflowing liquid 14, diverting a sample of the inflowing liquid creating a liquid inlet flow 20. As the liquid inlet flow 20 is under high pressure and temperature, the liquid inlet flow 20 is subjected to operational adjustments 22 prior to the liquid inlet flow 20 being in a condition for measurement of saturated steam quality. These operational adjustments 22 include reducing the liquid inlet flow's 20 operational temperature by passing the liquid inlet flow 20 through at least one inlet cooler 24 and reducing the liquid inlet flow's 20 operational pressure by passing the liquid inlet flow 20 through at least one inlet liquid valve 26. The resulting flow is an adjusted sample inlet flow 28.

An inlet measurement chamber 30 is in communication with the adjusted sample inlet flow 28. The inlet measurement chamber 30 has an inlet temperature compensated conductivity probe 32 that is submerged in the adjusted sample inlet flow 28. The inlet temperature compensated conductivity probe 32 is configured to measure the conductivity of the adjusted sample inlet flow 28. An inlet flow recovery drain 34 allows for the adjusted sample inlet flow 28 to be collected after passing the inlet temperature compensated conductivity probe 32.

A liquid separator outlet 40 is in communication with the post-boiler outlet flow stream 16 and diverts a sample of the post-boiler outlet liquid flow creating a sample stream 42. In this embodiment liquid outlet 40 is at least one liquid separator. The use of a liquid separator is merely illustrative. Those skilled in the art will recognize that other suitable apparatus may be used within the present system.

As the sample stream 42 is under high pressure and temperature, the sample stream 42 is subjected to operational adjustments 44 prior to the sample stream 42 being in a condition for measurement of conductivity. These operational adjustments 44 include reducing the sample stream's 42 operational temperature by passing the sample stream 42 through at least one outlet cooler 46 and reducing the sample stream's 42 operational pressure by passing the sample stream 42 through at least one outlet liquid valve 48. The resulting flow is an adjusted sample stream 50. In this embodiment, the operational temperature is a temperature less than the saturation point and the operational pressure is near ambient pressure.

An outlet measurement chamber 52 is in communication with the adjusted sample stream 50. The outlet measurement chamber 52 has an outlet temperature compensated conductivity probe 54 that is submerged in the adjusted sample stream 50. The outlet temperature compensated conductivity probe 54 is configured to measure the conductivity of the adjusted sample stream 50. An outlet flow recovery drain 56 allows for the adjusted sample stream 50 to be collected after passing the outlet temperature compensated conductivity probe 54.

A processor 60 is in communication with both inlet and outlet temperature compensated conductivity probes 32, 54, and is configured to calculate the saturated steam quality 62 of the post-boiler outlet flow 16. Additionally, processor 60 can calculate the level of saturated steam quality in a continuous manner, or at pre-established time intervals, such as once every second, or every 30 seconds. This will allow for an accurate measurement of the saturated steam quality at any time during operation of the boiler.

Processor 60 is further in communication with boiler control system 64 wherein the saturated steam quality 62 value can be transmitted to the boiler control system 64. The interface between processor 60 and boiler control system 64 can be any acceptable communication interface, including a hardwired output with multiple channels or a single Ethernet interface transmitting a variety of communication protocols. The boiler control system 64 can be configured to adjust boiler firing rate or liquid flow rate to achieve the desired steam quality.

Additionally, processor 60 can be configured to communicate with multiple boilers simultaneously. Further, a display device could be in communication with processor so that the steam quality measurement can be displayed.

Further, the system can be configured to operate automatically, i.e. without human involvement. This allows for the continual measurement of the saturated steam quality, which allows for the continual adjustments of the boiler operation.

FIG. 2 is a flowchart of an embodiment 100 of the method to measure saturated steam of the present invention. This embodiment 100 generally includes the steps of measuring pre-boiler conductivity of a liquid prior to entering a boiler 110, measuring post-boiler conductivity of the liquid exiting the boiler 112 and calculating the level of saturated steam quality 114 of the post-boiler outlet flow 16 based on the pre-boiler conductivity and post-boiler conductivity measurements. The calculating of level of saturated steam quality is performed by utilizing a processor 130. Following the calculating of the level of saturated steam quality, the result is transmitted to the boiler control system 128 so that the boiler control system can adjust the boiler fire rate and/or fluid flow rate.

Additional steps include adjusting the operational conditions of the liquid flow by reducing the operational temperature and pressure of the liquid flow prior to being measured both pre-boiler and post-boiler, 120, 124. Further, the measuring of the conductivity is performed by utilizing a temperature compensated conductivity probe 122, 126. Still further, an additional step can include the recovering the pre-boiler and post-boiler liquid after the conductivity measurement.

An additional embodiment of the present invention is directed toward the method set out above where the processor monitors the pre-boiler condition of a liquid prior to entering a boiler by detecting changes in the conductivity. The level of conductivity of the pre-boiler liquid is usually a relatively consistent value having a non-significant fluctuation in value. However, on occasion, the condition in the pre-boiler liquid changes beyond an acceptable value which can result in damage to the boiler. In this embodiment, the processor monitors the pre-boiler liquid's level of conductivity to determine if there is an unacceptable change thereof, and if such does occur, a notice and/or an alarm is sent to the boiler control system so that appropriate actions, such as shutting down the boiler, can take place in an effort to protect the boiler. The value which would be considered unacceptable can be a fixed value, one or more deviations away from the average value of the normal conductivity or any other value that could potentially result in damage to the boiler.

Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification. 

What is claimed:
 1. A method of determining saturated steam quality comprising the steps of: measuring pre-boiler conductivity of a liquid prior to entering a boiler; measuring post-boiler conductivity of the liquid exiting the boiler; and calculating the level of saturated steam quality of the post-boiler flow based on the pre-boiler conductivity and post-boiler conductivity measurements.
 2. The method of claim 1, further comprising the step of: cooling the pre-boiler liquid to an operational temperature.
 3. The method of claim 2, wherein the operational temperature is less than the saturation point.
 4. The method of claim 1, further comprising the step of: cooling the post-boiler liquid to an operational temperature.
 5. The method of claim 4, wherein the operational temperature is less than the saturation point.
 6. The method of claim 1, further comprising the step of: reducing pre-boiler liquid pressure to an operational pressure.
 7. The method of claim 6, wherein the operational pressure is near ambient.
 8. The method of claim 1, further comprising the step of: reducing post-boiler liquid pressure to an operational pressure.
 9. The method of claim 8, wherein the operational pressure is near ambient.
 10. The method of claim 1, further comprising the step of: recovering the pre-boiler liquid after the conductivity measurement.
 11. The method of claim 1, further comprising the step of: recovering the post-boiler liquid after the conductivity measurement.
 12. The method of claim 1 wherein the measuring of conductivity is performed by utilizing a temperature compensated conductivity probe.
 13. The method of claim 1 wherein the calculating of the level of saturated steam quality is performed by utilizing a processor based control system.
 14. The method of claim 13 wherein the calculating of the level of saturated steam quality is continuously calculated by utilizing the processor based control system.
 15. The method of claim 13 wherein the calculating of the level of saturated steam quality is calculated at a pre-established time interval by the processor based control system.
 16. The method of claim 13 further comprising transmitting level of saturated steam quality to the boiler control system.
 17. The method of claim 16 wherein all steps are automated and do not require human interaction.
 18. A system for determining saturated steam quality comprising: a liquid inlet in communication with a pre-boiler stream of liquid creating a liquid inlet flow; an inlet chamber in communication with the liquid inlet flow, the inlet chamber having a inlet temperature compensated conductivity probe that is submerged in the liquid inlet flow and configured to measure the conductivity of the inlet liquid; a liquid outlet in communication with a post-boiler outlet flow creating an outlet liquid flow; an outlet chamber in communication with outlet liquid flow, the outlet chamber having a outlet temperature compensated conductivity probe that is submerged in the outlet liquid flow and configured to measure the conductivity of the outlet liquid; and a processor in communication with the inlet and outlet temperature compensated conductivity probes and configured to calculate steam quality of the post-boiler outlet flow, the processor further in communication with boiler control system wherein boiler control system is configured to adjust boiler firing rate and/or liquid flow rate based on calculated steam quality of the post-boiler outlet flow.
 19. The system of claim 18, wherein the liquid outlet comprises at least one liquid separator.
 20. The system of claim 19, further comprising: an inlet cooler to reduce inlet liquid to operational temperature; at least one inlet liquid valve to reduce pressure of inlet liquid to operational pressure; an outlet cooler to reduce outlet liquid to operational temperature; at least one outlet liquid valve to reduce pressure of outlet liquid to operational pressure;
 21. The system of claim 20, wherein the operation temperature is less than the saturation point and the operational pressure is near ambient pressure.
 22. The system of claim 18 wherein the processor is in communication with multiple boilers.
 23. The system of claim 18 further comprising a display device to display steam quality measurement.
 24. A method of determining the condition of a liquid comprising the steps of: measuring pre-boiler conductivity of a liquid prior to entering a boiler; calculating the level of conductivity of the pre-boiler liquid based on the pre-boiler conductivity measurements of the liquid; transmitting a notice to the boiler control system in the event the measured conductivity exceeds a pre-determined limit value. 